Enzyme-mediated Ru@UiO-66@MnO NSs/thiamine-based ratiometric fluorescence sensor for visual detection of organophosphorus pesticide residues.

In view of the potential hazards of organophosphorus pesticides (OPs), this paper constructed a ratiometric fluorescent probe utilizing a functionalized metal-organic framework to detect OPs. Ru(bpy)Cl was encapsulated inside UiO-66 as a reference signal, and MnO nanosheets (MnO NSs) were grown on the surface to obtain Ru@UiO-66@MnO NSs. Acetylcholinesterase catalyzed the decomposition of acetylcholine into reductive thiocholine, which consumed MnO NSs, thus restoring the Ru@UiO-66 fluorescence. Due to the enzymatic inhibition of OPs and the redox reaction between MnO NSs and thiamine, this probe emitted blue fluorescence in the presence of OPs. The probe achieved linear responses to dichlorvos and chlorpyrifos with LODs of 9.99 × 10 μg mL and 9.99 × 10 μg mL. The probe exhibited a satisfactory recovery rate for OPs in green tea. Furthermore, a hydrogel detection platform was developed by embedding the probe into sodium alginate. Overall, this work provides a visual approach to detect OPs in agricultural products.